A semiconductor device chip (which includes numerous semiconductor devices) was traditionally mounted with its backside or substrate against another base substrate or heat sink surface to aid in cooling the device chip, and with its electrical contact pads on the opposite side facing upward for connection to an electrical circuit. The electrical contact pads were located near the periphery of the device chip to accommodate electrical connections. The electrical connections could be made, for example, by wire bonding, metallization techniques, or devices shaped like picture frames with electrical contacts on the underside which were used to physically sandwich the semiconductor device chip onto the substrate and also make electrical contact between the electrical pads on the device chip and the electrical pads on the substrate. All of these techniques are characterized by making all electrical connections at the periphery of the semiconductor device chip. See, for example, U.S. Pat. No. 4,150,420 to Berg and U.S. Pat. No. 3,984,620 to Robillard et al.
As the density and number of elements on the semiconductor device chip increased, so to did the size of the semiconductor device chip. However, difficulties were experienced in accommodating sufficient contact pads around the perimeter of the device chip to make all of the electrical connections that were desirable between the device chip and the surrounding base substrate.
The lack of sufficient space around the perimeter of the semiconductor device chip for contact pads was solved in a design that has come to be known as the "flip chip" module. The flip chip has electrical contact pads dispersed across the entire surface of the semiconductor device chip so that electrical contacts can be made to both the interior portion of the chip surface and the perimeter of the chip surface. However, it was necessary to invert (flip) the chip so that its backside or substrate surface was up (off the substrate) and the contact pads were down (against the substrate) to make electrical and physical contact with correspondingly located electrical terminals on the substrate. See, for instance, U.S. Def. Pub. No. T955,008 to Gregor et al, and U.S. Pat. Nos. 3,871,014 to King et al and 3,871,015 to Lin et al. While this increased the number of electrical connections between the semiconductor device chip and the substrate, it seriously inhibited the ability of the semiconductor device chip to dissipate heat, thereby degrading the performance of the device chip, limiting the conditions under which it could operate, and ultimately risking irreparable destruction due to excessive heat.
Others have attempted to solve this problem of heat dissipation by attaching devices to the backside of the device chip. This has included pistons that are spring loaded against the backside of the device chip, as illustrated in U.S. Pat. No. 4,246,597 to Cole et al, electrically insulative films attached to a thermally conductive material that is attached to the backside of the device chip, as illustrated in U.S. Pat. No. 4,092,697 to Spaight, and liquid metal contained against the backside of the device chip as illustrated in U.S. Pat. No. 4,323,914 to Berndlmaier et al. Each of these proposals for cooling the device chip has met with some success, but they are also extremely complex, difficult to manufacture, require an inordinate amount of space, place undesirable physical strains on the device chip, and do not provide the desired amount of cooling.
Thus, it is an object of the present invention to provide a simple and inexpensive apparatus for mounting a semiconductor device chip and making electrical connections thereto.
It is a further object of the present invention to provide apparatus for mounting a semiconductor device chip and making electrical connections thereto with the backside of the semiconductor device chip against a substrate while making electrical connections to electrical pads across the entire contact pad surface of the semiconductor device chip.
It is a still further object of the present invention to provide apparatus for mounting a semiconductor device chip and making electrical connections to electrical pads across the entire contact pad surface of the semiconductor device chip with the backside of the device chip against a heat conductive substrate.
These and other objects are accomplished with the apparatus of the present invention for mounting a semiconductor device chip and making electrical connections thereto. A substrate has a surface with electrical terminals. A semiconductor device chip has its backside connected to the surface of the substrate, and electrical pads across its upper surface. Means for electrically connecting the substrate electrical terminals and the electrical pads of the semiconductor device chip has first electrical contacts that are electrically connected to the contact pad surface of the semiconductor chip and second electrical contacts that are connected to the electrical terminals of the substrate. The first and second electrical contacts of the means for electrically connecting are electrically connected in a predetermined circuit.